Reduction of Process Steps via Multiphoton Optics' 3D Direct Laser Writing Technology
Due to its maskless 3D Direct Laser Writing technology, Multiphoton Optics’ Two-Photon Polymerization (TPP) process enables the generation of refractive and diffractive microoptical elements with arbitrary shapes in an arbitrary arrangement on a large variety of substrates.
This unlimited freedom of design is a unique feature compared to conventional techniques, and it thus provides the solution for novel device architectures to cope with the increasing demand of creating miniaturized devices with multiple functions.
Two scenarios exist to employ the technology in microlens fabrication. Firstly, individual microlenses or microlens arrays can be fabricated using LithoProf3D® directly on photonic chips, substrates or optical fibers which can be implemented in endoscopic devices for in- and outcoupling purposes. Secondly, replication masters can be manufactured, providing mass production capabilities of sophisticated optical designs.
Microlenses can be fabricated by our technology with a surface roughness of 2 to 4 nm, way below the critical value of λ/10 (with λ being the operation wavelength of the device). Thus, microlenses or microlens arrays for devices operating in the IR down to the VIS and the UV range can be created.
Single microoptical devices, arrays, or even combinations of differently shaped microlenses providing specially designed, novel imaging properties can be conveniently fabricated by LithoProf3D®. These lenses or lens arrays are, for example, employed for imaging and sensor products in all kind of application scenarios, where these sensor and imaging products are employed.
Assembly of Optoelectronic and Silicon Photonics Packaging
The assembly of optoelectronics and silicon photonics packaging requires accurate placement of components to ensure highly efficient light coupling for low optical loss. Additionally, beam shaping, and light guidance are essential for optimal illumination and relaxed alignment tolerances. Multiphoton Optics has developed a solution to eliminate 70 % of the usually required process steps to manufacture and align optical elements.
Applications examples for optoelectronic and photonics packages are
- Integrated microoptics for beam collimation in edge emitting laser sensors
- Expansion of effective area in high-speed photodiodes for datacom
- Microlens on laser die for beam shaping
- Microlenses on photodiodes
- Microlenses on VCSEL for ToF applications (e.g. LIDAR)
Application Example 1: Microlens on Laser Facet for Beam Shaping
Customer Use Case: The customer produces components for detectors. Infrared semiconductor (edge emitting) lasers (EEL) are used as light sources in gas detectors. Manufacturers of detectors require circular beam shapes for their devices. The elliptical beam shape originating from the EEL is thus a challenge. The legacy solution for beam shaping is to mount aspherical or cylinder lenses in front of the laser. The drawbacks are bulky packages and time-consuming costly manual labor resulting from active alignment and fixing.
Multiphoton Optics' technology enables the printing of lenses directly on the EEL’s facet. This allows further miniaturization of components, speeds up production of the packaged device and lowers overall production costs by up to 80 %.
Miniaturized packages fabricated with MPO’s technology have been constantly running for more 20,000 hours at an optical power density of more than 1 MW/cm2 with no evidence of degradation of the printed optics.
Application Example 2: Microlenses on Photodiodes
Customer Use Case: The customer is a manufacturer of VCSEL solutions and photodiodes (PD) for datacom transceivers (inter-board fiber connections). High-speed PDs with small active area present production and assembly challenges that cannot be solved with legacy solutions. One main challenge is achieving optimal alignment of the PD with the light source in the datacom transceiver package.
Multiphoton Optics' Solution: LithoProf3D® will directly print microlenses on PDs to enhance the effective area of the high-speed PD. The process will be integrated in the customer’s production workflow. This enables miniaturization while ensuring compatibility with assembly processes down the value chain.
Application Example 3: Microlenses on VCSEL for ToF Applications
Legacy Process: 3D sensing in smartphones is enabled by Time-of-Flight (ToF) applications. These applications are realized by implementing optical engines consisting of VCSEL arrays and microlens arrays for beam shaping. Due to the divergence of the VCSEL-emitted laser beam, the illumination is blurred at the edges resulting in suboptimal contrast. A perfectly collimated laser beam would result in better sensing specifications.
Additional applications: 3D cameras for AR/VR, in-cabin monitoring in automotive, LIDAR
Multiphoton Optics' Solution: TPP technology can be used to print collimating lenses directly on top of individual VCSELs to collimate the corresponding laser beam. Additionally, TPP technology can be used to create master or molds of complex MLA designs for beam shaping with new functionalities.
Fabrication of Complex Masters for Replication
Mastering of optical nanostructures or microlens arrays is the state-of-the-art solution for volume production with conventional replication technologies (e.g. NIL, injection molding). However, traditional master fabrication technologies cannot render complex designs and thus do not satisfy the increasing demand for novel optical functionalities. MPO can fabricate complex masters for replication thanks to its free-form capability and maskless laser writing exposure method.
Parallelization via replication of master structures provides a basis for increasing throughput and decreasing fabrication costs at the same time. With our key technology, arbitrarily shaped 3D master structures like individual microlenses of the same or of arbitrarily arranged shapes can be generated. Aside of microlenses, structures suitable for nanoimprint lithography jobs can be individually fabricated with the same approach, making use of the technology’s scalability from the 100 nm to the macro regime. These structures are then used to create a replication tool which then is be used to replicate the master structure on different substrates for a large variety of structure dimensions.
Application Example 1: TPP Master Fabrication
Legacy Process: Master or mold templates are used in replication processes (such as nano-imprint lithography, hot embossing or injection molding) for mass manufacturing (e.g. consumer electronics). The fabrication of these master templates can be very time and cost intensive with conventional technologies (e.g. for lens fabrication for smartphones: several months between different prototype series at costs above 100 k€). This affects the time-to-market from design optimization and validation to the final product.
Multiphoton Optics' Solution: TPP technology can be used to accelerate the prototyping phase in terms of costs and time. After the design has been validated, the final master can be fabricated with conventional technologies. Additionally, TPP technology can be used to create master or mold designs which cannot be realized with conventional technologies (e.g. special shaped MLAs) thereby enabling novel functionalities.
Application Example 2: Fresnel Lens for AR/VR Applications
Major players from the AR & VR equipment development and manufacturing space are facing several challenges: Currently available AR/VR glasses are heavy and bulky devices with low comfort for the users. Furthermore, the development of high image quality systems (resolution, field of view, contrast…) faces a bottleneck as legacy technologies are either not suitable to produce sophisticated designs (e.g. Fresnel lenses), require stitching that hinders functionality, or are time-consuming and expensive. This means that designs cannot be validated in a reasonable time frame, lengthening time-to-market in this competitive field.
Multiphoton Optics' Solution: LithoProf3D® will be the first technology platform (hardware + software) which will allow the fabrication of circular Fresnel lens molds without stitching artifacts, while maintaining high resolution (groove size < 1 µm) and accuracy (feature size < 1 µm). This will enable fast and easy prototyping of sophisticated optics for AR/VR technology, as well as other applications.
Biomedicine and Life sciences require increasing miniaturization of devices for non-invasive in vivo applications such as in endoscopy. Furthermore, mimicking the biological environment is crucial for cell growth.
Multiphoton Optics' technology can realize complex microstructures with advanced bio-compatible materials as required. Scaffolds and specially shaped surface structures or functions can be additively and subtractively created which are useful in Tissue Engineering applications. Further applications are possible in drug delivery systems or in microfluidics:
- Unique optical designs for endoscopy
- Complex designs for tissue engineering
- Microfilters with deterministic pore size
Application Example 1: Tissue Engineering
Customer Use Case: Scaffolds in 3D mimicking particular geometries are fabricated fast and reliably up to very large scales using Multiphoton Optics’ unique technology and equipment features. For the restoration of diseased or damaged tissue, the growth of cells on 3D porous scaffolds for tissue engineering is a promising approach to generate autologous tissue. Structure type and size can be simply varied to investigate their influence on primary human microvascular endothelial cells.
Application Example 2: Microfilters for Biomedical Applications
Customer Use Case: Our customer is a global provider of technologies and services for therapeutics. Commercially available membrane filters mainly consist of alternating polymer films (Cast Membranes) with statistic microcracks (induced by various methods) or of statistically arranged polymeric fibers (Cellulose). Resulting from the statistic distribution, the pore size of a specific filter is not clearly defined but exhibits a certain range which makes the characterization of a filter difficult.
Multiphoton Optics' Solution: With our micro 3D printing technology and its real 3D capability, the fabrication of a microfilter can be carried out according to a specific design, with controlled pore size and distribution, to meet individual customer requirements.
Application Example 3: Endoscope lenses
Customer Use Case: Endoscopes allow the observation for small body regions like blood vessels. Thin optical fibers are promising but require bulky conventional optics for imaging which increase the total form factor.
Multiphoton Optics' solution: Thanks to its print-on-device capability, Multiphoton Optics' technology enables the fabrication of miniaturized optical elements directly on the tip of a fiber.